Evaluation of the MycoDot test in patients with suspected tuberculosis in a field setting in Tanzania.

SETTING

Rapid, simple and inexpensive methods are needed to improve the diagnosis of tuberculosis in low-income countries. The MycoDot test has these characteristics.

OBJECTIVE

To assess the utility of the MycoDot test in screening patients with suspected tuberculosis.

DESIGN

Ambulatory patients presenting with symptoms of pulmonary tuberculosis were evaluated by physical examination and sputum acid-fast bacilli (AFB) microscopy. Separately, the MycoDot test was performed on whole blood. Patients with AFB-negative smears were treated with a 10-day course of erythromycin. Those remaining symptomatic had a chest radiograph. All sputum specimens were cultured for mycobacteria. Patients with culture-negative tuberculosis and those without a tuberculosis diagnosis were reassessed at 2 months.

RESULTS

Among the 241 patients who were evaluated, the MycoDot test was positive in 26% of patients with AFB-positive/culture-positive tuberculosis, 7% with AFB-negative/culture-positive tuberculosis, 7% with culture-negative tuberculosis, 19% treated for tuberculosis who did not meet study case definitions, and 16% without tuberculosis. Twenty four patients did not complete the assessment. Test sensitivity was 16%, specificity 84% and positive predictive value 45%. Sensitivity was highest (41%) in AFB-positive/HIV-negative patients and lowest (3%) in AFB-negative/HIV-positive patients.

CONCLUSION

The MycoDot test is not useful for the diagnosis of tuberculosis in sub-Saharan African countries, especially where HIV infection is prevalent.